658-74-2Relevant academic research and scientific papers
A new finding in selective Baeyer-Villiger oxidation of α-fluorinated ketones; a new and practical route for the synthesis of α-fluorinated esters
Kobayashi, Satoru,Tanaka, Hiroaki,Amii, Hideki,Uneyama, Kenji
, p. 1547 - 1552 (2007/10/03)
α-Fluorinated esters were effectively prepared by the Baeyer-Villiger oxidation of α-fluorinated ketones with m-chloroperbenzoic acid (m-CPBA) under mild conditions. The yield of the esters was influenced by the choice of solvent, base, and substituent on the aryl group of the ketones. 4-Methoxyphenyl substituted fluoroketones were oxidized almost quantitatively with m-CPBA within 10 min to 12 h at room temperature using 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as a cosolvent with CH2Cl2 (1:1, v/v) and aqueous buffer (KH2PO4-NaOH, pH 7.6) as an additive base. The oxidation reaction rates of α-fluorinated ketones were higher than those of the corresponding non-fluorinated ketones. The fluorine atom at α-position of fluoromethyl aryl ketones enhanced the reactivity in the Baeyer-Villiger oxidation.
A practical and highly efficient synthesis of α-(trimethylsilyl)-difluoro-acetates
Amii,Kobayashi,Uneyama
, p. 2001 - 2003 (2007/10/03)
An efficient method for the gram scale preparation of α-(trimethylsilyl)difluoroacetates is described. The key step involves Mg(0)-promoted selective C-F bond cleavage of readily available trifluoroacetates.
2-(Trifluoroacetyloxy)pyridine as a Mild Trifluoroacetylating Reagent of Amines and Alcohols
Keumi, Takashi,Shimada, Masakazu,Morita, Toshio,Kitajima, Hidehiko
, p. 2252 - 2256 (2007/10/02)
A new trifluoroacetylating reagent, 2-(trifluoroacetyloxy)pyridine (TFAP), was prepared by the reaction of 2-pyridinol and trifluoroacetic anhydride.TFAP has been found to be effective in the trifluoroacetylation of aliphatic and aromatic amines and alcohols including phenol under mild conditions.The reaction of p-nitrophenol with TFAP in ether gave the hydrogen-bonded complex between the phenol and 2-pyridone.This reagent has also been shown to be useful for the intramolecular dehydration of aldehyde oximes and amides to give nitriles in high yields.
Process for preparing compounds containing a difluoromethylene group in a position α to an oxygen atom
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, (2008/06/13)
A process for the preparation of compounds containing a difluoromethylene group in a position α to an oxygen atom. An alcohol or a phenol is brought into contact with trifluoroacetic acid or a halide or anhydride thereof in anhydrous liquid hydrofluoric acid, in the presence of boron trifluoride, in a quantity such that the absolute pressure of boron trifluoride is at least about one bar. The compounds obtained according to the invention are used as synthesis intermediates in the pharmaceutical, plant-protection, and dye industries, as anesthetics and as additives for lubricating oils.
OXIDATION BY THE SALTS OF METALS. VII. PLUMBATION AND OXIDATIVE SUBSTITUTION OF AROMATIC COMPOUNDS IN THE LEAD TETRAACETATE-LITHIUM CHLORIDE SYSTEM IN THE PRESENCE OF PERFLUORINATED CARBOXYLIC ACIDS
Serguchev, Yu. A.,Davydova, V. G.,Makhon'kov, D. I.,Beletskaya, I. P.
, p. 1006 - 1011 (2007/10/02)
The oxidation of benzene and substituted benzenes PhX with electron-donating (X = CH3, OCH3) and electron-withdrawing (X = Hlg, CF3, NO2) substituents in the Pb(OAc)4-LiCl system was investigated in the presence of perfluorinated carboxylic acids RfCOOH (Rf = CF3, C6F13).The reaction leads to the plumbation, chlorination, and acyloxylation products.It was shown that the reactions take place through the formation of aryl derivatives of lead(IV) with the participation of mixed-ligand complexes of lead.The products from the plumbation of toluene (in C6F13COOH in the absence of lithium chloride) and benzotrifluoro were isolated.In trifluoroacetic acid these intermediates undergo intramolecular redox decomposition with ligand transfer.The halogenobenzenes and benzotrifluoride are oxidized selectively in the CF3COOH-Pb(IV)-LiCl system, giving the corresponding aryl chlorides with yields close to quantitative (80-90percent).
Neutral Hydrolysis of Substituted Phenyl Trifluoroacetates in Water-Acetonitrile Mixtures with Low Content of Water
Neuvonen, Helmi
, p. 1141 - 1146 (2007/10/02)
The neutral hydrolysis of substituted phenyl trifluoroacetates has been studied in water-acetonitrile mixtures in the region 0.56-3.89M water.The large solvent deuterium isotope effect (kH2O/kD2O) of 2.3 and the thermodynamic activation parameters for the hydrolysis of 4-nitrophenyl and 2,4-dinitrophenyl trifluoroacetates are consistent with a reaction mechanism in which one water molecule acts as a nucleophile and one as a general base.A linear correlation with a slope of 3.4 is found between log kobs and log for the hydrolysis of 4-nitrophenyl trifluoroacetate.This indicates the incorporation of several water molecules in the transition state.The effect of the structure of the leaving group on the rate of the reaction is best explained by a rate-limiting attack on the carbonyl group.
